as this plays out, they now are convinced they have total visual environment, they are trying to evacuate any residents in the area from the neighborhood, and as was noted, now they went to move, the flash-bangs, be methodical. the one thing, they're not certain but they're operating under the assumption there are explosives in that yard. >> you know, i think one of the best examples for your viewers, i'm sure many of them saw "zero dark thirty." there was an initial assault phase, helicopters crashing in and all, then it seemed like minutes went by as people then started deliberately moving through and that's kind of a parallel to what you're going to see happen here tonight. but i think within a few hours of darkness, this could be favorably resolved. >> one of our producers is near the scene. lawrence, what are you seeing and hearing? >> well, i'm at washburn and chester streets, which is about a block from franklin street, where i'm told from a boston police source they have a suspect cornered in the backyard of a home. i'm also told that they're using flash-bangs to try to get him ou